Can relaxation lower metaboreflex-mediated blood pressure elevations?

Purpose: Relaxation can lower resting blood pressure, and this investigation sought to determine whether relaxation could reduce mean blood pressure (MBP) elevations produced by postexercise circulatory occlusion (PECO). Methods: Sixteen volunteers trained with relaxation and were able to decrease MBP at rest by at least 5 mm Hg within 2 min. Subjects performed four tests assigned randomly: i) rest with cuff occlusion, ii) rest and cuff occlusion with relaxation, iii) hand-grip exercise followed by PECO rest with cuff occlusion, and iv) hand-grip exercise followed by PECO with relaxation. Data for HR and MBP were collected using a Finapres; ratings of relaxation and discomfort from cuff occlusion were obtained using a 1- to 10-unit scale. Stroke volume (SV) and HR were collected from six subjects to calculate cardiac output and total peripheral conductance (TPC). Dependent variables were compared using an ANOVA. Results: HR (mean ± SD) was lower during both relaxation conditions as compared with control (-7 ± 4 bpm vs -2 ± 3 bpm; P < 0.05). The MBP was reduced during relaxation alone (-6 ± 3.7 mm Hg; P < 0.05) but not during PECO with relaxation. The rating of relaxation was higher during relaxation (6.8 ± 1.3 units) versus control (3.5 ± 1.2 units), but ratings were not different between relaxation conditions. Ratings of discomfort were higher during PECO (P < 0.05). Relaxation did not significantly alter CO or SV (N = 6). During relaxation alone, TPC was increased (0.046 ± 0.001 vs 0.049 ± 0.002 L·min^-1·mm Hg^-1; P < 0.05). However, TPC was significantly increased during PECO with relaxation. Conclusions: These findings suggest that although relaxation can affect cardiovascular regulation and lower HR and MBP at rest, this central signal cannot lower reflex increases in blood pressure originating from a peripheral metabolic stimulus.